Perspectives Online

Taking (biological) control

Studies by College Ph.D. candidate Sarah Thompson (holding a mole cricket) anticipate future integrated pest management needs for North Carolina's $4.5 billion turfgrass industry.
Photo by Art Latham

When the Turfgrass Council of North Carolina sponsored the 2005 annual Turfgrass Industry Conference and Expo in Winston-Salem in January, College of Agriculture and Life Sciences researcher Sarah Thompson was there.

Thompson, who holds a 2003 master's degree in entomology from the College and is a current Ph.D. candidate, told a seminar about her studies on the effectiveness of an alternative pest-control approach: using a microbe that kills the large and very mobile mole cricket, a top turf pest in the southeastern United States.

"Although we're still in beginning stages of this research," she said recently, "it's obvious that while biological controls will never replace conventional insecticides, they'll have an important role in pest management as time goes on."

Work on biological controls is part of a larger integrated pest management (IPM) approach, said Thompson, whose research is funded by the Center for Turfgrass Environmental Research and Education (CENTERE) at N.C. State University.

Why study mole crickets?

"It's impossible to conduct research on all pests," she said. "The mole cricket, since it's so damaging and very difficult to control as a soil pest, is a good place to start. If we are successful in controlling them with microbes, we know we have a chance to successfully manage other turfgrass insect pests with similar biological control agents.

"But," said Thompson, "we're researching biological control agents because it's a weak link in turfgrass IPM. We already have a lot of effective chemical and cultural control tools. Scientists are conducting research on biological controls, so if down the road, people need to integrate these strategies into their IPM programs, we'll be able to make good recommendations for effective use. Our goal is to stay ahead of the many regulatory actions that could potentially limit the chemical control options available to turfgrass managers."

She's gathering such information through several major studies with a mole cricket pathogen, Beauveria bassiana, using field and laboratory efficacy trials to determine appropriate strain and rate selection, product viability, and other critical factors for the use of this agent.

B.bassiana, a naturally occurring soil fungus, has been successful for the control of Mormon crickets and grasshoppers in the West as well as houseflies and beetles in poultry production houses.

Thompson points out a few benefits of microbial control: Hosts usually do not build up resistance and there is little effect on beneficial or nontarget organisms. Although frequently repeated applications may be needed for acceptable mole cricket control, many biocontrol agents can be applied with conventional spray equipment and don't leach into groundwater.

Thompson's research is in a rapidly growing area. North Carolina, with 12 turfgrass species, is eighth in total U.S. turf acreage: 2 million. Of those, 61 percent are in home lawns; 54,000 acres cover 600 golf courses; 610,000 acres are by roadsides.

"As our population grows, so does our irrigated turfgrass acreage, which means the needs of the industry will continue to grow as well, necessitating the research that is being conducted in the turfgrass program here at NC State," she said.

The CENTERE currently funds many projects that focus on minimizing potential negative effects of turfgrass management on the surrounding environment through the use of best management practices and IPM approaches. Researchers plan to continue to develop new environmentally friendly strategies to manage insects, weeds and diseases.

Thompson works under the direction of entomology professor Dr. Rick Brandenburg and crop science professor Dr. Tom Rofty, who are co-directors of the CENTERE, and crop science professor Dr. Fred Yelverton. Brandenburg and Yelverton are also specialists with the North Carolina Cooperative Extension Service.

-Art Latham